Some semiconductor devices, such as transistors, include one or more layers overlying a dielectric layer. For example, transistors are typically formed by depositing a dielectric layer and forming one or more gate layers over the dielectric layer. A hard mask layer is formed over the one or more gate layers. Thereafter, the hard mask layer and the one or more gate layers are patterned to form gate structures. Source/drain regions are formed by implanting ions on opposing sides of the gate structures. To create various doping profiles in the source/drain regions, spacers are frequently used. Spacers are formed alongside the gate structures by depositing a conformal dielectric layer and performing an anisotropic etch, thereby removing the dielectric layer from flat regions of a substrate while leaving a spacer alongside the gate structure. The spacers, among other things, protect the dielectric layer under the gate layers.
After forming the gate structure, the hard mask layer is usually removed. To remove the hard mask, a photoresist layer is formed over the gate structures and an etch-back process is performed to expose the hard mask layer, while remaining portions of the photoresist layer protect the spacers, isolation regions (e.g., shallow trench isolations, field oxide regions, or the like), and source/drain areas. Once exposed, the hard mask layer may be attacked.
During the etch-back process, however, the photoresist material alongside the gate structure may be recessed too far such that, when the hard mask layer is removed, a portion of the dielectric may be exposed and damaged, thereby adversely affecting the operation of the resulting device.